Dioximes as antifoggants in silver halide emulsions



United States Patent This invention relates to photographic materialsandI more particularly to a method forpreventing the formation offog andblack spots in'photog'raphic emulsion with dioximecompounds.

' It has'been well known that a photographic emulsion on storage tendsto become spontaneously developable without exposure'to light. There isnormally a'detectable amount of silver salts reduced during developmentin the areas where no exposure was given;.this is commonly called fog.The formation of fog is promoted by bad conditions in storage as well asbad conditions in development. When a photographic material wetted bydeveloping solution is exposed to air in development, the formation offog is particularly promoted and we call it airial fog hereinafter.Moreover fog is also formed by the presbe more remarkably prevented.

ence of fine iron particles or other fine impurity particles containedin supports, gelatin or chemicals. These impurity particles may alsoenter into photographic materials during the production or treatment ofthem. And in this case particularly spot-like fog having a high, opticaldensity, which is generally called black spot is usually formed. 7 1. 1

For preventing the formation of such airial fog and black spots theadditions of various compounds have been proposed, but their eifects areusually weak and even though some of them are effective they give otherbad 'influen'cesysuch as, reduction of sensitivity, deterioration of thequality of gelatin layers, etc.

We. havefound thatthe formation of airial fog and black spots can beremarkably suppressed by-the addition of compounds shown by thefollowing general Formu laI.-" w:

' 1 |IOH won R-'-o (oHz)n-oR" (I) (Wherein R and R each representsa'hydrogen atom, a lower alkly group, an aryl' group, aheterocyclicgroup containing an oxygen atom or a nitrogen atom, or a Icarboxyl'group and nrepresents 0, l or 2.) in an emulsion layer and/or aprotective layerof halide photographic materials.

Representative compounds of the above mentioned general Formula I, whichcan be used in this invention, are as follows: i

silver NOH NOH II II Q-C-CHr-C-Ca 3,393,072 Patented July 16, 1968 NOHNOH I The compounds of this invention may be used individually or may beused as a mixture of two or more of 3 these compounds. Further, inanother embodiment of this invention the compoundof the above generalformula may be used with salicylaldoxime or its derivatives shown by thefollowing general Formula II p CH=NOH (Wherein R" and R each representsa hydrogen atom,

OH group, or a lower alkyl group.)

whereby the formation of airial fog and black spots can Representativecompounds of the general Formula II which can be used in this inventionare as follows.

@CH=NOH CI-I=NOH @CH=NOH I on,

and

It has been already disclosed in B.P. 623,448 that a salicylaldoxime isused for preventing the formation of airial fog but when thesalicylaldoxime is used with 7 at any stage of the production ofemulsions but it is preferable to add them after ripening and beforecoating. There are no limitations for the amount of them but the amountof compound (I) is suitably 350 g., and more preferably 10-20 g. per 1kg. of gelatin in a silver halide photographic emulsion layer or aprotective coating layer. Further, when compound (II) is used togetherwith compound (I), the amount of compound (II) is suitably 10-100 g. andmore preferably 20-50 g. per 1 kg. of gelatin in a silver halidephotographic emulsion layer or a protective coating layer.

A silver halide photographic emulsion that is used in this invention maybe or may not be optically dye sensitized. Moreover, the silver halidephotographic emulsion may be chemically sensitized with asulfur-containing compound, a noble metal salt, a polyoxyethylenederivative, a polyamine, or a quaternary ammonium salt and also in orderto improve the photographic characteristics it may contain awater-soluble polymer such as polyvinyl pyrrolidone. Further, in caseswhere a silver halide photographic emulsion contains a hardening agent,such as, formaline or mucochloric acid, a natural or synthetic surfaceactive agent, and a stabilizer such as a tetraazindene compound, theaddition of the dioxime compound of this invention in the emulsion cansuppress effectively the formation of airial fog and black spots withoutreducing the desirable photographic properties of the photographicmaterial endowed by the addition of these additives.

Example 1 A photographic sulfur sensitized, gold sensitized andoptically cyanine dye sensitized high-speed panchromatic silveriodobromide emulsion for negative type photographic material, whichcontain 5 mole percent of silver iodide was dissolved by heating andadded with fine particles of iron which had been prepared preliminaryfor promoting the formation of black spots caused artifically, Thesolution was divided into four equal volume portions after stirring for10 minutes. Each of the divided solutions was added with above-statedcompound (2) in the amount shown below and coated on a film basefollowed by drying. After developing for 10 minutes at 20 C., fixing,rinsing with water and drying, the sizes of formed black spots and thenumbers of thus formed spots per 0.3 sq. m. were detected, which wereshown below.

Amount of N o. of spots No. of spots No. of spots compQund (2) of 21-2mm. diam. of 0.9-0.1 mm. below 0.09 mm. (gJkg. gelatin) No changes wereobserved in the photographic properties as well as the physicalproperties of the emulsion layers.

The composition of the used developing solution was as follows:

Warm water cc 500.0 Metol g 2.0 Sodium sulfite (anhydrous) g 100.0Hydroquinone g 5.0 Borax g 20.0

Water to 1.0 liter.

Example 2 Amount of compd. Size of spot Relative optical (3)(g./kg.gelatin) (diam.nm1.) density of spot When compound (5) was usedinstead of compound (3), almost the same results were obtained.

Example 3 A photographic sulfur sensitized and optically merocyanine dyesensitized high contrast orthochromatic silver bromochloride emulsioncontaining 30 mole percent of silver iodide was added with compound (2)in the amount shown below and coated on a film base then dried. Forincreasing airial fog artificially, the photographic material wasdeveloped as follows. That is, the photographic film was immersed in adeveloping solution for 1 minute at 20 C., exposed in air for 1 minute,and then immersed again in the developing solution for 1.5 minutes.After fixing, rinsing with water, and drying, the optical density of theformed airial fog is as follows:

Amount of compound (2),

( g./ kg. gelatin) Optical density The composition of the developingsolution was as follows:

War-m water ml 500.0 Sodium sulfite (anhydrous) g 30.0 Paraformaldehydeg 7.5 Acid sodium sulfite g 2.2 Boric acid g 7.5 Hydroquinone g 22.5Potassium bromide g 1.6 Water liters to 1.0

Example 4 A protective coating layer for the high-contrastorthochromatic silver chlorobromide photographic emulsion in Example 3was added with above-mentioned compound {2 1) and treated as in Example3. The results are shown elow.

Amount of compd. (1) Optical density (g./kg. gelatin): of air fogs Whenabove-shown compound (6) was used instead of using compound (1), almostthe same results were obtained.

Example 5 Amount of compd. (2) Amount of compd. (8) Optical density ofair fog (gJkg. gelatin) (gJkg. gelatin) When compounds (9), (10) and(11) were used respectively instead of compound (8), almost the sameresults were obtained.

Example 6 Amount of compd. (1) Amo(unt of coinpd. (9) Optical density ofg air (gJkg. gelatin) .llrg. gelatin) tog What we claim is:

1. A silver halide photographic material comprising a support and asilver halide photographic emulsion layer, said emulsion layercontaining at least one compound shown by the general Formula I NOH NOHxii-wrrm-h-rv (I) wherein R and R each represents a member selected fromthe class consisting of a hydrogen atom, a lower alkyl group, an arylgroup, a heterocyclic group containing an oxygen atom, a heterocyclicgroup containing a nitrogen atom, and a carboxylic group and nrepresents 0, l and 2.

2. A silver halide photographic material comprising a support and asilver halide photographic emulsion layer, said emulsion layercontaining at least a compound shown by the general Formula I NOH NOHwherein R and R each represents a member selected from the classconsisting of a hydrogen atom, a lower alkyl group, an aryl group, aheterocyclic group containing an oxygen atom, a heterocyclic groupcontaining a nitrogen atom, and a carboxylic group and n represents 0, 1and 2, and at least one compound shown by the following general FormulaII (In-I OH=NOH wherein R" and R each represents a member selected fromthe class consisting of a hydrogen atom, OH group, and a lower alkylgroup.

3. A silver halide photographic material comprising a support, a silverhalide photographic emulsion layer, and a protective layer for theemulsion layer, at least one of said layers containing at least acompound shown by the general Formula I NOH NOH wherein R and R eachrepresents a member selected from the class consisting of a hydrogenatom, a lower alkyl group, and aryl group, a heterocyclic groupcontaining an oxygen atom, a heterocyclic group containing a nitrogenatom, and a carbocyclic group and n represents 0, 1 and 2.

4. A silver halide photographic sensitive material comprising a support,a silver halide photographic sensitive emulsion layer, and a protectivelayer for the emulsion layer, at least one of said layers containing atleast a compound shown by the general Formula I NOH NOH wherein R and Reach represents a member selected from the class consisting of ahydrogen atom, a lower alkyl group, an aryl group, a heterocyclic groupcontaining an oxygen atom, a heterocyclic group containing a nitrogenatom, and a carboxylic group and n represents 0, 1 and 2, and a compoundshown by the following general Formula II R (II) wherein R and R eachrepresents a member selected firom the class consisting of a hydrogenatom, OH group, and a lower alkyl group.

References Cited FOREIGN PATENTS 623,448 5/1949 Great Britain. 533,03411/1956 Canada.

NORMAN G. TORCI-IIN, Primary Examiner.

R. E. FICI-ITER, Assistant Examiner.

2. A SILVER HALIDE PHOTOGRAPHIC MATERIAL COMPRISING A SUPPORT AND ASILVER HALIDE PHOTOGRAPHIC EMULSION LAYER, SAID EMULSION LAYERCONTAINING AT LEAST A COMPOUND SHOWN BY THE GENERAL FORMULA I